JPQL 'Function' doesn't send operator

Question

I am using EclipseLink over Spring Boot and have this jpql in a repository:

    @Query("select function('pMonth',p.payDay) ,sum(p.price) " +
            "from FullPayment p where " +
            "group by function('pMonth', p.payDay)"
    )
    List<Object[]> paymentMonthlyHistory();

but it does not send the operator p.payDay calling my custom function pMonth. Here is the database error:

Internal Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Incorrect number of arguments for FUNCTION adventure_db.pMonth; expected 1, got 0
Error Code: 1318
Call: SELECT pMonth(), SUM(PRICE) FROM panel_fullPayment WHERE ((PAYDATE >= ?) AND (TRANSACTIONAMOUNT >= PRICE)) GROUP BY pMonth()
    bind => [1 parameter bound]

I use Mysql as DBMS. Any help would be appreciated

Answer 1

The problem was a typo. The field name is payDate but I wrote p.payDay. I put the answer here to emphasize that if you mistype the field name here, it won't show you an error on boot, but will generate a wrong query.